Ongoing and planned cross-sectional studies include populations exposed to benzene, chlorinated solvents, disinfection byproducts. polycyclic aromatic hydrocarbons, arsenic, and selected pesticides. On-going case-control studies of stomach, esophagus, brain, bladder, renal cell and breast cancer, NHL, and benzene-induced hematotoxicity and hematologic malignancies and cohort studies of women in China and agricultural workers in the United States are evaluating a range of potential genetic risk factors and their interaction with occupational and environmental exposures. Many of these studies are also collecting tumor samples for future molecular analyses.